Auxiliary workpiece supporting means for precision grinding machines

ABSTRACT

In a precision grinding machine including mutually spaced workpiece supporting assemblies rotatable about a common axis and each incorporating a relatively fixed clamping jaw disposed to support one end of a workpiece during successive workpiece unloading and loading operations and a cooperating relatively movable clamping jaw selectively movable into and out of engagement with a workpiece supported in the cooperating relatively fixed clamping jaw; auxiliary work supporting means mounted upon each workpiece supporting assembly adjacent to its relatively fixed clamping jaw, operative, whenever the relatively movable clamping jaw is released, to support and remove a portion of the weight of the workpiece off the adjacent relatively fixed clamping jaw, including, means operative to facilitate axial and/or angular rotary movement of a workpiece engaged by the auxiliary supporting means for precise axial and/or angular positioning of the workpiece relative to the respective relatively fixed clamping jaws.

United States Patent Joyce AUXILIARY WORKPIECE SUPPORTING MEANS FORPRECISION GRINDING MACHINES Inventor: Glover C. Joyce, Worcester, Mass.

Assignee: The Warner 8r Swasey Company,

Cleveland, Ohio Filed: Apr. 26, 1971 Appl. No.: 137,481

[111 3,728,824 1451 Apr. 24,1973

Primary Examiner-Harold D. Whitehead Attorney-Thomas L. Tarolli andCalvin G. Covell [5 7 ABSTRACT [52] U.S. Cl ..51/l05 SP, 51/237 CS outof engagement with a workpiece supported in the [51] lnt.Cl. ..B24b 5/42cooperating relatively fixed clamping jaw; auxiliary [58] Field ofSearch ..5l/l05,237 work supporting means mounted upon each workpiecesupporting assembly adjacent to its relatively [56] References Citedfixed clamping jaw, operative, whenever the relatively movable clampingjaw is released, to support and UNITED STATES PATENTS remove a portionof the weight of the workpiece off 3,583,108 6/1971 015111 ..51 237 csthe adjawnt relatively fixed clamping j including, 3,006,118 10/1961Fournier ....S1/277 CS means operative to facilitate axial and/orangular ro- 2,950,586 8/1960 Smith ..51/237 CS tary movement of aworkpiece engag d by th a nm- 3,034,268 5/1962 Smith. ..5l/237 CS ryupporting means for precise axial and/ r angular 3,142,941 8/1964Fourmer ..5l/105 SP positioning of the workpiece relative to therespective relatively fixed clamping jaws.

13 Claims, 8 Drawing Figures l 55' I 1 w I l 1 xii 760 x I 762:1 II- 452I I 14 -$z I42 Patented April 24, 1973 2 Sheets-Sheet 1 WWW INVENTORGLOVE}? C. Jo YCE BY w, gav /Z7 A (3 F. N T

Patented April 24, 1973 2 Sheets-Sheet 2 2 kw \mnk mvNmv INVENTOR G LOVER C. Joyce I AG E N T AUXILIARY WORKPIECE SUPPORTING MEANS FORPRECISION GRINDING MACHINES BACKGROUND OF THE INVENTION 1. Field ofInvention The instant invention contemplates auxiliary workpiecesupporting means for relatively heavy workpieces required to beprecisely located within and supported by a machine tool arranged toperform a machining operation thereon, and particularly for heavyworkpieces required to be precisely positioned within and supported by aprecision grinding machine arranged to perform one or more grindingoperations thereon.

2. Description of the Prior Art It is known to provide work restsbetween the centers of a pair of spaced work supports for the purpose ofsupporting and aligning a heavy workpiece prior to being engaged, pickedup, and supported by the centers. However, the applicants auxiliary worksupport means differs from the prior art in that they have rotatableworkpiece engaging members and are supported by and rotatable with thework supports for the purpose of reducing sliding friction by supportinga portion of weight of the workpiece during axial and/or angulardisplacements of a heavy workpiece relative to the frictionally engagingwork supports. For example, a relatively heavy elongated workpiece suchas a crankshaft deposited in a precision grinding machine for thepurpose of grinding its main bearing or pin bearing surfaces, issupported in the grinding machine in the manner illustrated in [1.8.Pat. No. 3,142,941 granted Aug. 4, 1964 to Fournier, for example, bymeans of a pair of opposed spaced workpiece supporting assemblies eachprovided with a pair of opposing clamps arranged to frictionally engageand fixedly secure one end portion of each crankshaft deposited in thecrankpin grinding machine.

Typical grinding operations on such workpieces require precise axialand/or angular orientation relative to the grinding wheel before therespective ends of the workpiece are secured between the opposing clampsincorporated in each of the respective workpiece supporting assemblies.

SUMMARY OF THE INVENTION Auxiliary work supports including low frictionfreely rotatable work engaging members mounted on levers or piston rodsare mounted on axially spaced work supports rotatable about a commonaxis. There are either resilient and/or fluid actuated means forautomatically biasing the auxiliary work supports into supportingengagement with portions of the workpiece adjacent precision worklocating bearing surfaces on clamping jaws fixed to the work supports.Movable clamping jaws are operable in the well known manner to clamp theworkpiece against the bearing surfaces of the fixed jaws after it hasbeen displaced relative thereto to properly align portions of theworkpiece with the cutting tool or grinding wheel of a machine tool.Upon releasing the movable clamping jaws the resilient or fluid actuatedmeans applies a predetermined amount of force to move the auxiliary worksupports suffrciently to support and remove a portion of the weight ofthe heavy workpiece from the bearing surfaces of the fixed clampingjaws. Thus the sliding frictional resistance between the workpiece andthe bearing surfaces is substantially reduced by the freely rotatablework engaging members to allow subsequent easier axial and/or angularrotary displacements of the workpiece by axial and/or angular workpositioning mechanisms on the machine tool.

Therefore, an object of this invention is to provide auxiliarysupporting means for a workpiece, operative automatically to facilitateits precise displacement relative to workpiece supporting assemblies inwhich the workpiece is deposited.

Another object of this invention is to provide auxiliary supportingmeans for a workpiece operative automatically to facilitate axialdisplacement of the workpiece relative to workpiece supportingassemblies in which it is deposited.

Still another object of this invention is to provide auxiliarysupporting means for a workpiece operative automatically to facilitateangular rotary movement of the workpiece relative to workpiecesupporting assemblies in which it is deposited.

Yet another object of this invention is to provide auxiliary supportingmeans for a workpiece operative automatically to facilitate both axialand angular displacements of the workpiece relative to workpiecesupporting assemblies in which it is deposited.

A further object of this invention is to provide first and second setsof auxiliary supporting means for a workpiece selectively operative,respectively, to facilitate axial movement of the workpiece relative toworkpiece supporting assemblies in which it is deposited, and tofacilitate angular rotary movement of the workpiece relative toworkpiece supporting assemblies in which it is deposited.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows an end view, partially insection, of an auxiliary work supporting means for a workpiece arrangedto facilitate axial movement of the workpiece relative to a pair ofworkpiece supporting assemblies in which it is deposited; i

FIGS. 2a and 2b show side elevations, partially broken away, of onesuitable arrangement for mounting the respective auxiliary supportingmeans shown in FIG. 1 in the respective workpiece supporting assembliesof a machine tool. and illustrating the operative relationship betweenthe respective auxiliary workpiece supporting means and portions of atypical elongated workpiece supported in the respective workpiecesupporting assemblies;

FIG. 3 is a detailed view, partially broken away, of a portion of theinstant invention illustrated in FIG. 1 and FIGS. 2a and 2b, modified tofacilitate angular rotary rather than axial movement of the workpiecerelative to the workpiece supporting assemblies in which it isdeposited;

FIG. 4 is a detailed view, partially broken away, of a portion of theinstant invention illustrated in FIG. 1 and FIGS. 20 and 2b, modified tofacilitate both axial and angular movement of the workpiece relative tothe workpiece supporting assemblies in which" it is deposited;

FIG. 5 illustrates an alternative embodiment of the instant inventionincorporating separate sets of auxiliary workpiece supporting meansselectively operative to facilitate axial movement of the workpiece andto facilitate angular movement of the workpiece, and additionallyillustrates actuating means for the auxiliary workpiece supporting meansfor facilitating axial movement of the workpiece operative concurrentlywith means for precisely locating the workpiece axially relative to theworkpiece supporting assemblies in which it is deposited;

FIG. 6 is a section taken on line 66 of FIG. further illustratingdetails of the means for precisely locating the workpiece axially; and

FIG. 7 illustrates actuating means for the auxiliary workpiecesupporting means for facilitating angular displacements of the workpieceoperative concurrently with means to rotate a crankshaft to positiondifferent crankpins thereon successively in the proper position for agrinding operation thereon.

DESCRlPTlON OF THE PREFERRED EMBODIMENTS By example only, the inventionwill be described in combination with a machine tool such as crankpingrinding machine comprising a pair of rotatable work support assembliesfor supportingly engaging opposite end portions of a crankshaft and onwhich the auxiliary work support means of the instant invention aremounted; means for rotating, angular indexing, and axially displacingthe crankshaft relative to the work support assemblies to preciselyalign crankpins to be ground with the grinding wheel.

A typical crankpin grinding machine including the necessary means, withwhich the instant invention can be used in combination, and incorporatedby reference is disclosed in the Fournier et al. US. Pat. No. 3,142,941granted Aug. 4, 1964 and to which reference may be had for details notdisclosed herein. The typical crankpin grinding machine referred to hasa pair of spaced coaxial work support assemblies or pot chucks 117 and118 rotatably mounted ona pair of work heads 115 and 116 and supportinga crankshaft W for rotation about an axis of a crankpin to be groundgenerally parallel to the cutting face and axis of the grinding wheel21;-

Since the respective crankpins of a crankshaft are angularly offset thecrankshaft is rotated about its axis relative to the pot chuckassemblies after each crankpin is ground, in the manner and by the meansdisclosed, to bring the axis of the next crankpin to be ground intoalignment with the common axis of rotation of the pot chucks. In mostinstances each crankpin' is also displaced axially relative to the potchucks into alignment with the grinding wheel 21 by the endwise locator31 to provide what is known as a spark splitting operation in thedisclosed manner.

The crankshaft W is located and supported by the pot chucks when thefront and rear main bearings thereof are in frictional engagement withthe bearing surface of the half bearing 35 which also serve as the fixedclamping jaws of the clamping assemblies 25 and 27 on the pot chucks 117and 118. Each of the clamping assemblies 25 and 27 includes the fixedjaw or half bearing 35 and a releasable movable clamping jaw 37 coactingwith the fixed jaw or half bearing 35 to secure a workpiece in the potchucks 117 and 118 for rotation therewith.

The instant invention provides auxiliary work support means adapted tobe mounted on each of the pot chucks 1 17 and 118 for the purpose ofsubstantially reducing sliding friction by removing a portion of weightof the workpiece off the surfaces of the half bearings 35 when arelatively heavy workpiece W must be axially and/or angularly displacedrelative to work supporting assemblies or pot chucks 117 and 1 18.

Each of the auxiliary work supports 140 comprises an adjustable base orbase plate 142 adapted to be fixed in any suitable manner, as bybolting, to a portion of the pot chucks 117 and 118 adjacent the halfbearings 35. A plurality of adjusting screws 144 are threaded intothreaded holes in the plate 12 and extend into engagement with the potchuck. By adjusting the screws 144 the base plate can be raised orlowered relative to the pot chucks and thereafter fixed thereto in theadjusted position by one or more bolts 146.

On and extending away from the base plate 142 is a U-shaped bearingsupport portion or block 142a having spaced parallel portions with holesin which are preferably fixed a pair ofspaced axially aligned sleevebearings or bushings 148 which may also be a pair of needle or ballbearings. A pivot pin 150 extends between and into the spaced bearings148 with its axis substantially parallel to the axis of rotation of thepot chucks 117 and 118 and the workpiece W.

Pivotally mounted in the U-shaped block 142a and about the pivot pin 150is a lever or pivotal member 152 having intermediate its opposite ends ahole through which the pivot pin 150 extends and suitably fixed to thelever by a set screw 154. The pivotal member or lever 152 has a stoparmportion 152a on one side of the axis of the pivot pin 150 and in whichan adjustable stop screw 156 is threaded and locked in adjusted positionby a lock nut 158. On the opposite side of the axis of the pivot pin 150the lever 152 has a support arm or head portion l52b with a cavity, slotor pocket 1520 therein suitable for accommodating a freely rotatable lowfriction workpiece engaging member 160 of the desired type and size.-

In FIGS; 1 to 3 inclusive the cavity, slot or pocket 152c is of a shapeand size to accommodate a roller 160 which may be the outer raceof ananti-friction roller or ball bearing assembly, or as shown a plainroller rotatably mounted on a bearing shaft or journal 162 fixed to thesupport arm l52b by a set screw. The roller 160 is positioned to rotatefreely about the axis of the shaft 162 extending transversely andsubstantially at right angles to the pivot axis of the pivot pin .150and the direction in which the workpiece is displaced rela tive to thework support means 117 and 118.

Resilient means of any suitable type, such as, the spring 164 shownlocated between the base plate 142 and the lever 152 can be provided tobias the support arm portion l52b together with the low or anti-frictionwork engaging member 160 away from the base plate 142 and the stop armportion together with the stop screw 156 toward the base plate 142. Theopposite ends of the spring 164 extend into recesses and are seatedagainst the opposing recessed surfaces in the support arm portion 152band the base plate 142'. The spring 164 is of any commercially availabletype of sufficient predetermined size and capacity to exert apredetermined amount of force, when compressed, to

at least support a portion of the weight of the workpiece W and reducethe degree of frictional engagement between the workpiece and thebearing 35.

It can be seen that when the movable clamping jaw 37 releases theworkpiece W, the force exerted by the spring 164 will also overcome anycohesiveness causing the workpiece W to stick to the half bearings 35.By adjusting the stop screw 156 the portion of weight of the workpiecetaken off the half bearing 35 and the degree of frictional resistancebetween the half bearing 35 and the surface of the workpiece W can bevaried. For example the bearing surfaces of crankshaft W shown inphantom lines in FIGS. 2a and 2b could be, but are preferably not,completely disengaged from the surfaces of the half bearings 35. Thusthe crankshaft would be more easily displaced relative to pot chuckssince there would be substantially less frictional sliding resistanceand only two points of rolling contact between the rotatable workengaging members 160 and the circular main bearing surfaces of thecrankshaft W.

In FIG. 3 there is shown a modified form of the inventiori wherein alever 172 can be substituted for the lever 152 to facilitate easierrotary and angular displacements of the workpiece on freely rotatablework engaging members. The lever 172 is substantially the same as butdiffers from the lever 152 in that it has a support arm portion 172bwith a cavity, slot, or pocket 172C and a work engaging member 160aarranged to rotate freely about the axis of a bearing shaft or journal162a that extends parallel to the pivot axis of the pivot shaft 150 andat a right angle to the direction of movement of the workpiece W beingdisplaced relative thereto, indicated by the arrow.

Another modification of the invention shown in FIG. 4 provides anotherlever 182 that may be substituted for both the levers 152 and 172. Thelever 182 has a support arm portion 182b which differs from that oflevers 152 and 172 in that it has a semicircular or generallyhemispherical cavity, socket or pocket 182C and a pair ofangularlyspaced narrow low friction bearing shoes or pads 182d therein fixed tothe support arm portion 182b.

Engaging, supported, and freely rotatable on the bearing pads 182d is aspherical work engaging member or ball bearing 16% that protrudes out ofthe cavity. Retaining means such as the retaining cap or plate 184 isfixed as by bolting to the support arm l82b and has an opening of apartial semi-circular or hemispherical shape through which the otherhalf of the spherical work engaging member or ball bearing l60bprotrudes. A pair of angularly spaced retaining low friction bearingpads or shoes 184a are fixed within the opening to the retaining cap 184to maintain the ball bearing 160b in place.

The spherical work engaging member l60b is confined by the low frictionbearing pads and free to rotate in any direction within them. Thereforethe heavy workpiece W engaged and supported thereby can be easilydisplaced both axially and angularly about its axis with two points ofrolling frictional engagement between it and the balls 160b rotatedthereby.

In FIGS. 5, 6, and 7 there is shown still another embodiment of theinvention wherein auxiliary work support means 200 comprising at leastone piston and cylinder device 20] mounted on each pot chuck 117 and118, are provided and adapted to be connected into and actuated by thefluid pressure control system of a machine tool, such as disclosed inUS. Pat. No. 3,l42,94l referred to above as an example.

Each piston and cylinder device 201 comprises a cylinder 202 with acylinder bore 202a therein. Each cylinder 202 can be either a separateunit suitably attached to or constructed as an integral part of the potchucks 117 and 118. This being a matter of preference and design notshown and deemed to be unnecessary to a clear understanding of theinvention by those of ordinary skill in the art. A piston or plunger 204is slideably mounted in the cylinder bore 202a and has a piston rod 205extending from the piston or plunger 204 and through one end portion orend cap fixed to the cylinder 202. Fixed to the end of the piston rod isa U- shaped holder, block or clevis 206 which is only one example of themany possible means which may be provided for supporting a bearing shaft208, and a low friction freely rotatable workpiece engaging member orroller 210 thereon. At the opposite end of the cylinder is an end capfixed to the cylinder and a suitable passage or threaded hole connectedin the conventional manner to a line, pipe or conduit for conveyingfluid under pressure from a suitable fluid pressure system.

Stop means are provided'for limiting the stroke of the piston and hencethe portion of weight of the workpiece supported by the auxiliarysupport means 200. The stop means may comprise a predetermined fixedstroke of the piston relative to the cylinder wherein a shoulder oneither the piston or piston rod 205 butts against the end of thecylinder 202. Preferably the stop means is adjustable and comprises arod 212 extending from the opposite end of the piston 204 and theopposite end of the cylinder 202. The rod 212 is slideable in the end ofthe cylinder and sealed in the conventional manner, not shown, toprevent fluid from escaping thereby and has a threaded end portion onwhich are threaded a stop nut 214 and a lock nut 216.

I The stop nut 214 engages the cylinder to limit the stroke of piston204 and can be adjusted to vary the stroke and hence the portion ofweight of the workpiece supported by each of piston and cylinder devices201 and the auxiliary support means 200.

As shown, there are three fluid actuated piston and cylinder devices 201on the auxiliary workpiece support means 200 associated and cooperatingwith each of the work support assemblies 117 and 118 for a total of sixdevices 201 on the machine. One of a pair or first set of piston andcylinder devices 201 of the auxiliary workpiece support means 200 isarranged on each of the pot chucks 117 and 118 substantially in a planeC and to facilitate an axial displacement of the workpiece W androtation of roller 210 about an axis of the hearing shaft 208 situatedat substantially a right angle to the direction of axial displacementand the axis X of rotation of the workpiece W relative to the pot chucks117 and 118.

Another pair of two pairs or second sets of piston and cylinder devices201 of the auxiliary work support means 200 are mounted in planes D andE on opposite sides of plane C and the first set of devices 201. Theyare arranged to engage the workpiece W at substantially equal angulardistances from the plane C passing through the axis X of the workpieceand the point of contact of the roller 210 of the first set of auxiliarysupport means 200. Rotary angular displacements of the workpiece arefacilitated by the two pairs or second sets of devices 201 of theauxiliary work support means 200 since each of the work engaging membersor roller 210 is positioned for rotation about the axis of the bearingshaft 208 substantially parallel to the axis X and right angles to thedirection of displacement of the workpiece.

Referring to FIG. 5, there is shown how connecting conduits and thefirst set of piston and cylinder devices 201 of the auxiliary worksupport means 200 can be tied in or connected with the fluid pressuresystem, the cylinder 56 of the endwise locator, steadyrest, and gageassembly 31, and port B of the directional control valve V9 disclosed inthe above mentioned U.S. Pat. No. 3,142,941 to facilitate axialdisplacements of the crankshaft W.

In operation, after a crankshaft W is deposited in the pot chucks 117and 118 and engaged by the locating pin 63 of the angular positioningmechanism 61 or rotated by the angular indexing mechanism, a crankpin tobe ground is positioned between the grinding wheel 4 21 and the endwiselocator assembly 31. Thereafter,

the fluid directional control valve V9 is actuated by the energizationof solenoid S9 actuating valve V9 whereby fluid under pressure in line Ppasses to a port, line, or conduit B to both the cylinders 56 and 202 ofthe pair or first set of fluid actuated piston and cylinders 201. As aresult a predetermined portion of the weight of the workpiece W issupported and engaged by only the first set of devices 201 of theauxiliary support means 200 during the simultaneous axial movement ofthe workpiece W by the endwise locator 31 in the manner disclosed in theU.S. Pat. No. 3,142,941 referred to. Upon de-energization of solenoid S9valve V9'resets and fluid under pressure in line P passes to port, lineor conduit A to cylinder 56 to reset the endwise locator 31 and fluidexhausts from the cylinders 202 of the first set of devices 201 throughline B to port, line or conduit T. The total weight of the crankshaft orworkpiece W is then supported by the half bearings 35 having asubstantial amount of area of frictional engagement with the workpiece Wfor the purpose of aligning and clamping the workpiece against movementduring grinding thereof.

FIG. 7 discloses one method of connecting conduits and the two pairs orthe second set of fluid actuated piston and cylinder devices of theauxiliary work support means 200 situated on planes D and E of each ofthe pot chucks 117 and 118 to port A of control valve V19 of the fluidpressure control system disclosed in U.S. Pat. No. 3,142,941.

Prior to depositing a crankshaft W in the pot chucks 117 and 118 andbefore each rotary displacement of the crankshaft W by the angular indexmechanism the valve V19 is actuated as shown by energization of asolenoid S19. Shifting of valve V19 causes fluid under pressure in port,line or conduit P to pass into port, line or conduit B andsimultaneously to both the clutch assembly 81 and each pair of thesecond set of the devices 201 situated in planes D and E on the potchucks 117 and 118.

Only one of the first set and two of the second sets of piston andcylinder devices 201 of the fluid actuated auxiliary work support means200 and one of the pot chucks 117 and 118 has been shown since the otheris substantially a duplication thereof connected to the fluid conduits Aand A by conduits or lines as indicated by the legend To 118". Fluidunder pressure in conduit B forces the piston 82 of the clutch assembly81 toward the left as shown to disengage the locating pin 85 from thepot chuck 117 and allow rotation of the crankshaft W together with thepiston 82 and locating pin 85 relative to the pot chucks 117 and 118 andshifts the pistons 204 and rollers 210 of the two pairs of the secondsets of devices 201 of the auxiliary work support means 200 forsupporting engagement with the workpiece W. As taught, one of thecontrol valves V16, V17 or V18, only one of which is shown, is actuatedsubstantially at the same time as the valve V19 by the energization ofone of the respective solenoids S16, S17 or S18. Fluid under pressurethen passes from port, line or conduit P through port, line or conduitB" to one of the cylinders 16, 17 or 18 of the particular individualactuating means 47 connected thereto and moves the camming roller 46 ofthe respective camming element assembly 41 into engagement with theproper crankpin of the rotating crankshaft W previously released by themovable clamping jaws 37 in the manner taught in U.S. Pat. No.3,142,941. Fluid exhausts from the opposite sides of the cylinders 16,17 or 18 and 83 through the respective ports, lines or conduits A" and Athrough control valves V19, and V16,

V17 or V18 to exhaust ports, lines or conduits T" and r Upon completionof the angular indexing and displacement of the crankshaft or workpieceW, solenoids S19 and S16, S17 or $18 are de-energized and valves V19,and V16, V17 or V18 reset. Fluid under pressure passes from ports P andP" to ports or conduits A' and A to opposite sides of cylinders 83 and16, 17 or 18 .moving the piston 82, the locating pin 85 into thelocating hole 86, the drive pin 63 further into the flange of thecrankshaft W and retracting the individual actuating means 47 with thecamming element 46 out of the rotating path of the crankshaft W.

Fluid exhausts from ports A and A to ports T and T". The weight of theworkpiece W is now fully supported by the half bearings 35, the rollers210 move slightly away from the workpiece W, and the pistons are resetin the cylinders 202 as a result of the fluid exhausting therefrom andthe absence of pressure therein.

Shortly after completing the rotary angular indexing operation andbefore the workpiece is fully clamped against movement solenoid S9 isenergized actuating control valve V9, the endwise locator 31, and thefirst pair or set of devices 201 of the auxiliary work support means 200for axially displacing the crankshaft or workpiece W relative to the potchucks 117 and 118 and the grinding wheel 21.

As disclosed in U.S. Pat. No. 3,142,94l theaxial displacement of thecrankshaft takes place when the lever 58 on assembly 31 contacts thenewly angularly indexed crankpin to be ground and actuates a limitswitch 9LS energizing time delay relay 4TR which energizes time delayrelay STR energizing S9 of valve V9 for a period of time sufficient toaxially displace the crankshaft W. Thereafter STR times de-energizing Swhich initiates the movement of the clamping jaws 37 to clamp theworkpiece W securely against the half bearing 35 and the de-energizationof S9 of valve V9 to retract the endwise locator and the first pair orset of devices 201 of the auxiliary work support means 200 before thecrankpin is ground.

Preferably the movement of and force applied by the auxiliary worksupports is predetermined and incorporated in their design, to helpsupport a portion of the weight of the workpiece W. Thus the slidingfriction created between the half bearing 35 and substantially heavyworkpiece is reduced and converted to rolling friction allowingdisplacements thereof to be accomplished with much less effort andenergy by rolling frictional contact with the auxiliary work supportmeans.

Since many variations may be made of the invention without departingfrom the spirit thereof it is to be understood that the embodimentsillustrated and disclosed hereinabove are not to be considered in alimiting sense and includes all modifications thereof contemplatedwithin the scope of the appended claims.

What is claimed is:

1. In combination with a machine tool of the type having work supportmeans, including clamping means that frictionally engage a portion of aworkpiece, for aligning and clamping the workpiece placed thereinagainst relative movement and releasable for allowing the workpiece tobe displaced relative to the work support means and positioning theworkpiece for engagement with a cutting tool, and

means for displacing the workpiece relative to the work support meansand. positioning the workpiece for engagement with a cutting tool,wherein the improvement comprises:

auxiliary work support means on the work support means, operable whenthe workpiece is released by the clamping means, for supporting andremoving a portion of weight of the workpiece off the clamping means,and providing rolling engagement with the workpiece to facilitateprecise displacements of the workpiece by the displacing means, saidauxiliary work support means comprising:

at least one piston and cylinder device mounted adjacent each of theclamping means and having a cylinder fixed adjacent each of the clampingmeans on the work support means and each cylinder having a cylinder boretherein;

a piston slidable in the cylinder bore;

a piston rod extending from the piston, out an end of the cylinder, andtoward the workpiece in the work support means;

a rotatable workpiece engaging member mounted for rotation about itsaxis on an end portion of the piston rod;

biasing means, for moving the piston, together with the piston rodrelative to the cylinder and forcing the rotatable workpiece engagingmember into supporting engagement with the workpiece;

stop means, for limiting the relative movement between the piston andcylinder and the portion of weight of the work-piece supported by theauxiliary work support means;

a pair of piston and cylinder devices angularly spaced about the portionof the workpiece adjacent each of the clamping means with the pistonrods and their axes converging toward each other and operable tosimultaneously direct the rotatable workpiece engaging members thereoninto supporting rolling engagement with different angularly spaced areason the portion of the workpiece adjacent each of the clamping meansduring a rotary displacement of the workpiece relative to the worksupport means.

2. In combination with a machine tool for working on a crankshaft and ofthe type having work support means, including clamping means thatfrictionally engage the crankshaft, for aligning and clamping acrankshaft placed therein againstrelative movement and releasable forallowing the crankshaft to be displaced relative to the work supportmeans and positioning the crankshaft for engagement with a cutting tool,and

means for displacing thecrankshaft relative to the work support meansand positioning the crankshaft for engagement with a cutting tool,wherein the improvement comprises:

auxiliary work support means disposed on the work support meansoutwardly of the clamping means, operable when the crankshaft isreleased by the clamping means, for supporting and removing a portion ofweight of the crankshaft off the clamping means, and providing rollingengagement with the crankshaft to facilitate precise displacements ofthe crankshaft by the displacing means,

said auxiliary work support means comprising a rotatable workpieceengaging member having a circular outer surface disposed in engagementwith a cylindrical outer surface of the crank-shaft outwardly of theclamping means; and

mounting means for enabling said rotatable workpiece engaging member toroll along the cylindrical outer surface of the crankshaft upon movementof the crankshaft relative to the work support means.

3. The combination according to claim 2 wherein the auxiliary worksupport means further comprises:

a lever pivotally mounted outwardly of the clamping means on the supportmeans, for movement about a pivot axis, and having an end portionmovable about the pivot axis toward and away from the cylindrical outersurface of the crankshaft;

the rotatable workpiece engaging member and mounting means beingdisposed on the end portion of the lever for rotation about its axis;and

biasing means, engaging the lever, for forcing the rotatable workengaging member into supporting engagement with the cylindrical outersurface of the crankshaft.

4. The combination according to claim 3 wherein the auxiliary supportmeans further comprises:

stop means for limiting pivotal movement of the lever, the end portion,and the rotatable workpiece engaging member about the pivot axis awayfrom the work support means and the portion of weight of the crankshaftsupported .by the auxiliary work support means.

5. The combination according to claim 4 wherein the stop meanscomprises:

adjustable means, attached to the lever, for varying the pivotalmovement of the lever and the portion of the weight of the crankshaftsupported by the auxiliary work support means.

6. The combination according to claim wherein the auxiliary supportmeans further comprises:

a base plate fixed adjacent the clamping means on the work supportmeans;

a pivot support extending from the base plate and having a pivot holeabout the pivot axis; and

a pivot pin in the pivot hole and on which the lever is mounted forpivotal movement.

7. The combination according to claim 2 wherein the rotatable workpieceengaging member is a roller rotatable, by the cylindrical outer surfaceof the crankshaft about an axis of rotation at substantially a rightangle to a direction of movement in which the crankshaft is displaced.

8. The combination according to claim 2 wherein this mounting meanscomprises:

surface means defining a socket; and

the rotatable work engaging member is a sphere rotatable in anydirection within the socket and having a portion thereof protruding outof the socket for rolling engagement with the cylindrical surface of thecrankshaft.

9. The combination according to claim 2 wherein the auxiliary worksupport means comprises:

at least one piston and cylinder device mounted outwardly of each of theclamping means and having a cylinder fixed adjacent each of the clampingmeans on the work support means and each cylinder having a cylinder boretherein having a central axis ex-' tending transversely to a centralaxis of the cylindrical outer surface of the crankshaft;

a piston slidable in the cylinder bore;

a piston rod extending from the piston, out an end of the cylinder, andtoward the crankshaft in the work support means;

the rotatable workpiece engaging member being supported by said mountingmeans for rotation about its axis on an end portion of the piston rod;

biasing means, for moving the piston, together with the piston rodrelative to the cylinder and forcing the rotatable workpiece engagingmember into supporting engagement with the cylindrical outer surface ofthe crankshaft; and

top means, for limiting the relative movement between the piston andcylinder and the portion of the crankshaft supported by the auxiliarywork support means.

10. The combination according to claim 1 wherein the auxiliary worksupport means comprises:

three of the piston and cylinder devices arranged with at least onepiston and cylinder device fixed between the pair of angularly spacedpiston and cylinder devices adjacent the clamping means with its pistonrod axis at substantially equal angles from the axes of the pair of thepiston rods and operable to direct and force the rotatable workpieceengaging member thereon into supporting rolling engagement with anotherarea of the portion of the workpiece adjacent the clamping means duringan axial displacement of the workpiece relative tothe work supportmeans. 11. The combination according to claim 10 wherein the stop meanscomprises adjustable means, for varying the movement of the pistonrelative to the cylinder and the portion of weight of the workpiecesupported by the auxiliary work support means. 12. The combinationaccording to claim 11 wherein the biasing means comprises a source offluid under pressure conveyed into the cylinder bore and applied againstthe piston during displacements of the workpiece by the displacingmeans. 13. The combination according to claim 12 wherein the rotatableworkpiece engaging member is a roller rotatable by the workpiece aboutan axis of rotation situated at substantially a right angle to adirection of movement of the workpiece being displaced.

1. In combination with a machine tool of the type having work supportmeans, including clamping means that frictionally engage a portion of aworkpiece, for aligning and clamping the workpiece placed thereinagainst relative movement and releasable for allowing the workpiece tobe displaced relative to the work support means and positioning theworkpiece for engagement with a cutting tool, and means for displacingthe workpiece relative to the work support means and positioning theworkpiece for engagement with a cutting tool, wherein the improvementcomprises: auxiliary work support means on the work support means,operable when the workpiece is released by the clamping means, forsupporting and removing a portion of weight of the workpiece off theclamping means, and providing rolling engagement with the workpiece tofacilitate precise displacements of the workpiece by the displacingmeans, said auxiliary work support means comprising: at least one pistonand cylinder device mounted adjacent each of the clamping means andhaving a cylinder fixed adjacent each of the clamping means on the worksupport means and each cylinder having a cylinder bore therein; a pistonslidable in the cylinder bore; a piston rod extending from the piston,out an end of the cylinder, and toward the workpiece in the work supportmeans; a rotatable workpiece engaging member mounted for rotation aboutits axis on an end portion of the piston rod; biasing means, for movingthe piston, together with the piston rod relative to the cylinder andforcing the rotatable workpiece engaging member into supportingengagement with the workpiece; stop means, for limiting the relativemovement between the piston and cylinder and the portion of weight ofthe work-piece supported by the auxiliary work support means; a pair ofpiston and cylinder devices angularly spaced about the portion of theworkpiece adjacent each of the clamping means with the piston rods andtheir axes converging toward each other and operable to simultaneouslydirect the rotatable workpiece engaging members thereon into supportingrolling engagement with different angularly spaced areas on the portionof the workpiece adjacent each of the clamping means during a rotarydisplacement of the workpiece relative to the work support means.
 2. Incombination with a machine tool for working on a crankshaft and of thetype having work support means, including clamping means thatfricTionally engage the crankshaft, for aligning and clamping acrankshaft placed therein against relative movement and releasable forallowing the crankshaft to be displaced relative to the work supportmeans and positioning the crankshaft for engagement with a cutting tool,and means for displacing the crankshaft relative to the work supportmeans and positioning the crankshaft for engagement with a cutting tool,wherein the improvement comprises: auxiliary work support means disposedon the work support means outwardly of the clamping means, operable whenthe crankshaft is released by the clamping means, for supporting andremoving a portion of weight of the crankshaft off the clamping means,and providing rolling engagement with the crankshaft to facilitateprecise displacements of the crankshaft by the displacing means, saidauxiliary work support means comprising a rotatable workpiece engagingmember having a circular outer surface disposed in engagement with acylindrical outer surface of the crank-shaft outwardly of the clampingmeans; and mounting means for enabling said rotatable workpiece engagingmember to roll along the cylindrical outer surface of the crankshaftupon movement of the crankshaft relative to the work support means. 3.The combination according to claim 2 wherein the auxiliary work supportmeans further comprises: a lever pivotally mounted outwardly of theclamping means on the support means, for movement about a pivot axis,and having an end portion movable about the pivot axis toward and awayfrom the cylindrical outer surface of the crankshaft; the rotatableworkpiece engaging member and mounting means being disposed on the endportion of the lever for rotation about its axis; and biasing means,engaging the lever, for forcing the rotatable work engaging member intosupporting engagement with the cylindrical outer surface of thecrankshaft.
 4. The combination according to claim 3 wherein theauxiliary support means further comprises: stop means for limitingpivotal movement of the lever, the end portion, and the rotatableworkpiece engaging member about the pivot axis away from the worksupport means and the portion of weight of the crankshaft supported bythe auxiliary work support means.
 5. The combination according to claim4 wherein the stop means comprises: adjustable means, attached to thelever, for varying the pivotal movement of the lever and the portion ofthe weight of the crankshaft supported by the auxiliary work supportmeans.
 6. The combination according to claim 5 wherein the auxiliarysupport means further comprises: a base plate fixed adjacent theclamping means on the work support means; a pivot support extending fromthe base plate and having a pivot hole about the pivot axis; and a pivotpin in the pivot hole and on which the lever is mounted for pivotalmovement.
 7. The combination according to claim 2 wherein the rotatableworkpiece engaging member is a roller rotatable, by the cylindricalouter surface of the crankshaft about an axis of rotation atsubstantially a right angle to a direction of movement in which thecrankshaft is displaced.
 8. The combination according to claim 2 whereinthis mounting means comprises: surface means defining a socket; and therotatable work engaging member is a sphere rotatable in any directionwithin the socket and having a portion thereof protruding out of thesocket for rolling engagement with the cylindrical surface of thecrankshaft.
 9. The combination according to claim 2 wherein theauxiliary work support means comprises: at least one piston and cylinderdevice mounted outwardly of each of the clamping means and having acylinder fixed adjacent each of the clamping means on the work supportmeans and each cylinder having a cylinder bore therein having a centralaxis extending transversely to a central axis of the cylindrical outersurface of the crankshaft; a piston slIdable in the cylinder bore; apiston rod extending from the piston, out an end of the cylinder, andtoward the crankshaft in the work support means; the rotatable workpieceengaging member being supported by said mounting means for rotationabout its axis on an end portion of the piston rod; biasing means, formoving the piston, together with the piston rod relative to the cylinderand forcing the rotatable workpiece engaging member into supportingengagement with the cylindrical outer surface of the crankshaft; and topmeans, for limiting the relative movement between the piston andcylinder and the portion of the crankshaft supported by the auxiliarywork support means.
 10. The combination according to claim 1 wherein theauxiliary work support means comprises: three of the piston and cylinderdevices arranged with at least one piston and cylinder device fixedbetween the pair of angularly spaced piston and cylinder devicesadjacent the clamping means with its piston rod axis at substantiallyequal angles from the axes of the pair of the piston rods and operableto direct and force the rotatable workpiece engaging member thereon intosupporting rolling engagement with another area of the portion of theworkpiece adjacent the clamping means during an axial displacement ofthe workpiece relative to the work support means.
 11. The combinationaccording to claim 10 wherein the stop means comprises adjustable means,for varying the movement of the piston relative to the cylinder and theportion of weight of the workpiece supported by the auxiliary worksupport means.
 12. The combination according to claim 11 wherein thebiasing means comprises a source of fluid under pressure conveyed intothe cylinder bore and applied against the piston during displacements ofthe workpiece by the displacing means.
 13. The combination according toclaim 12 wherein the rotatable workpiece engaging member is a rollerrotatable by the workpiece about an axis of rotation situated atsubstantially a right angle to a direction of movement of the workpiecebeing displaced.